Method of repairing a throttle valve cable assembly

ABSTRACT

The present invention is a replacement throttle valve cable assembly and method of use for an automatic transmission of a land vehicle, which permits repair of the throttle valve cable without unnecessary replacement of serviceable components such as the cable housing and linkage clip components. This is accomplished by the use of a cable stop device or so-called adjustment stud, which permits transmission shift performance to be fine-tuned by temporary adjustments to the cable length prior to permanent installation. The adjustment stud includes a temporary setscrew fastener integrally connected to a permanent swage fastener by an undercut shear zone. Once the cable length is established and the vehicle road tested, the swage fastener is permanently installed on the cable. Thereafter, the segmented portion of the adjustment stud containing the setscrew is snapped off at the shear zone along with any excess cable by a suitable tool.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit under 35 U.S.C.§ 119(e) of U.S.Provisional Patent Application No. 60/367,740 filed Mar. 28, 2002,entitled Throttle Valve Cable Assembly and Method of Use.

BACKGROUND OF THE INVENTION

The present invention relates to automatic transmissions and, moreparticularly, to a replacement throttle valve cable assembly for GeneralMotors GM 4L60, GM3T40, GM4T60, THM 200, THM 325-4L, and THM 200-4R(hereinafter “GM transmissions”).

Automotive vehicles with carbureted engines utilize a throttle valvecable, which attaches to the throttle valve linkage at one end thereofand is connected to a throttle valve control lever on the transmissionhousing. The throttle valve (hereinafter “TV”) cable is routed from thethrottle body in the engine compartment under tension passing through acable housing and bends to conform to mounting brackets located on theengine and transmission to be secured on the throttle valve of thetransmission.

The length of the TV cable is critical to proper shift performance. Ifthe TV cable is shortened, both line pressure and shift points will beraised. Alternatively, if the TV cable is lengthened, both line pressureand shift points are lowered. Operating the vehicle with a longer TVcable causes premature clutch wear and other transmission malfunctions.

The TV cable is subject to mechanical wear and fraying and musteventually be replaced at periodic maintenance intervals. At present theoriginal equipment manufacture for the GM transmissions provides thethrottle valve cable only in a predetermined length in a completeassembly, which requires the replacement of otherwise serviceablecomponents such as the cable housing and linkage clip along with the TVcable. This involves significant replacement costs for the vehicle ownerwhen repair of the TV cable is necessary. Many vehicle owners would liketo override the predetermined factory setting of the throttle valvecable, tailor the shift points or shift feel of the vehicle, and reducerelated service and labor costs.

There are known prior art patents that are available in the field ofthrottle valve cables and cable fittings and their discussion follows.One example of a prior art throttle valve cable is disclosed in U.S.Pat. No. 5,638,721 to Lee and also in U.S. Pat. No. 5,727,425 to Lee,which teach a method and apparatus for adjusting a throttle valve cablein an automatic transmission. In these patents a sleeve and spring areinstalled at the distal end of the throttle valve cable between thecable end clamp and the tear-drop shaped cable end fitting on thethrottle valve cable. The spring opposes movement of the cable endfitting toward the distal end of the throttle valve cable so that thecable end fitting is at its maximum distal position only at fully openthrottle. This gives the vehicle operator the shift feel of a shorterthrottle valve cable at most throttle openings. The sleeve and springare installed only on throttle valve cables in automatic transmissionsthat do not have throttle valve cable end fittings permanently attachedto a throttle cam.

An example of a throttle cable fitting structure is shown in U.S. Pat.No. 5,046,380 to Matsumoto et al. which discloses a throttle valveoperating cam of an automatic transmission and an output control memberof an automotive engine interconnected so as to cooperate with eachother by a cable consisting of an outer tube and an inner cable.

Another example of a cable adjustment device for an automotive throttlebody is shown in U.S. Pat. No. 5,295,408, to Nagle et al. whichdiscloses an adjustable cable strand end fitting for use in adjustingthe slack or tension in a cable strand attached through the fitting to athrottle body moveable member.

U.S. Pat. No. 5,174,170 to Kato et al. and U.S. Pat. No. 4,869,123 toStocker disclose cable length adjustment and cable position controldevices, which may be considered relevant to the present invention.

While these devices fulfill their respective, particular objectives andrequirements, the aforementioned patents do not disclose the throttlevalve cable assembly including the cable adjustment stud of the presentinvention, which substantially departs from the conventional conceptsand designs of the prior art.

SUMMARY OF THE INVENTION

Accordingly, the present invention is a Throttle Valve (hereinafter“TV”) Cable Assembly provided in kit form, which permits replacement andadjustment of the TV cable without unnecessary replacement ofserviceable components such as the cable housing and linkage clip. Thepresent TV Cable Assembly features a cable stop device, which allowstransmission shift timing to be fine-tuned by making repeatedadjustments to the cable length prior to permanent installation of thecable. This is accomplished by use of a so-called cable adjustment studincluding a temporary setscrew fastener integrally connected with apermanent swage fastener by an undercut shear zone. Once the TV cablelength is properly set, the swage fastener or swedge is crimped to thecable to complete the permanent installation. Thereafter, the segmentedportion of the adjustment stud containing the setscrew fastener isloosened and snapped off at the shear zone along with any excess cableby a suitable tool such as pliers. The adjustable length of the presentTV Cable Assembly provides a universal fit to many different GMtransmissions.

There has thus been outlined, rather broadly, the important features ofthe invention in order that the detailed description thereof thatfollows may be better understood, and in order that the presentcontribution to the art may be better appreciated. There are additionalfeatures of the invention that will be described hereinafter and whichwill form the subject matter of the claims appended hereto.

Those skilled in the art will appreciate that the conception upon whichthis disclosure is based may readily be utilized as a basis for thedesigning of other structures, methods, and systems for carrying out thepurposes of the present invention. It is important, therefore, that theclaims be regarded as including such equivalent constructions insofar asthey do not depart from the spirit and scope of the present invention.

Other features and technical advantages of the present invention willbecome apparent from a study of the following description and theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the present invention are set forth in theappended claims. The invention itself, however, as well as otherfeatures and advantages thereof will be best understood by reference tothe following detailed description of an illustrative embodiment whenread in conjunction with the accompanying figures, wherein:

FIG. 1 is an elevational view of a Throttle Valve Cable Assembly beinglabeled Prior Art;

FIG. 2 is a diagrammatic view of the throttle valve of the GMtransmissions being labeled Prior Art;

FIG. 3 is an elevational view of the Throttle Valve Cable Assembly ofthe present invention; and

FIG. 4 is an elevational view of the adjustment stud of the presentinvention installed on the TV cable.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Prior to describing the TV Cable Assembly of the present invention, itmay be beneficial to review a TV Cable Assembly of the prior art forpurposes of comparison. With reference to FIG. 1 there is shown thereina TV Cable Assembly in accordance with the prior art, indicatedgenerally at 100 and illustrated in FIG. 1. The TV Cable Assembly 100 iscomprised of a two-part cable housing, indicated generally at 115,including mounting brackets 116, 117, a linkage clip 120, cable stop125, cable connector 130, and cable 135.

The throttle valve cable 135 is disposed within the housing 115 insliding engagement therewith and also extends through the linkage clip120, which is permanently captured thereon by a swage block or swedge125. On carbureted GM vehicles the cable 135 is attached at a first endthereof by the linkage clip 120 to the linkage rod (not shown), whichopens the carburetor or throttle body. The opposite end of the cable 135is coupled via the cable connector 130 to the throttle valve controllever 150 (FIG. 2) on the side of the transmission housing, whichactuates the throttle valve, indicated generally at 200, within thetransmission.

The throttle valve 200 (FIG. 2) monitors the engine throttle positionand allows lower-speed shifts when the vehicle speed is relatively lowcompared with the engine throttle opening. The throttle valve 200 itselfis a spool-type valve that uses a spring 205 and plunger 210 to opposemainline hydraulic pressure acting through its inlet port as at 142.When the engine throttle is opened by pressing down on the acceleratorpedal, the cable 135 via the linkage clip 120 pulls the throttle valvecontrol lever 150 and compresses the spring 205, applying pressure tothe throttle valve in the transmission. As shown in FIG. 2 this causesthe throttle valve 200 to open the throttle pressure outlet port as at140, which releases hydraulic pressure to fluid circuits within thetransmission. Fluid pressure from the throttle valve 200 is routed tothe opposite side of the shift valve to balance governor pressureagainst throttle position, which allows shifting to occur at the correcttime.

The length of the TV cable is critical to proper shift performance. Ifthe TV cable is shortened, both line pressure and shift points will beraised. Alternatively, if the TV cable is lengthened, both line pressureand shift points are lowered. The road speeds at which each shift occurscan be fine-tuned by adjustments to the length of the TV cable in the GMtransmissions. The present invention has been developed to facilitatesuch adjustment and to resolve other shortcomings of the prior art.

Referring to FIG. 3 there is shown therein a TV Cable Assembly inaccordance with the present invention, indicated generally at 10. Itwill be understood that in accordance with the present invention, theoriginal equipment manufacture (hereinafter “OEM”) cable housing 115with brackets 116, 117 and the linkage link 120 may be reused ifserviceable and that only the universal cable 135′ including a new cableconnector 130 and the adjustment stud, indicated generally at 25, arereplaced when using the present invention.

In practical use of the present invention, the new universal cable 135′including a cable connector 130 preinstalled at a first end thereof isfabricated to a predetermined length that is sufficient to accommodateeach of the aforementioned GM transmissions. In accordance with thepresent invention, a new cable adjustment stud 25 is installed at theopposite end of the cable 135′ to complete the installation as explainedhereinafter in further detail.

As shown in FIG. 4 the adjustment stud 25 is a segmented construction,which effectively comprises two separate fastening devices. Moreparticularly, the adjustment stud 25 includes a swage fastener 26 and asetscrew fastener 28 integrally connected by an undercut shear zone asat 30. The shear zone 30 is designed to allow physical separation ofswage fastener 26 and setscrew fastener 28 by a manual tool such aspliers after installation is complete.

In the preferred embodiment the adjustment stud 25 is fabricated from amalleable metal such as copper C11000 per American Society of Testingand Materials (ASTM) B187-97 or other suitable material in theconfiguration shown in FIG. 4.

The adjustment stud 25 provides structures comprising cable lengthadjusting means including, but not limited to, the following structures.The adjustment stud 25 includes a through bore 32 wherein thereplacement cable 135′ resides after assembly. At least one setscrew 35positioned within the setscrew fastener 28 portion engages matingthreads 36 extending into the bore 32. A second setscrew 35 (notillustrated) may be advanced into threads 36 from the opposite side ofthe fastener 28 if desired.

It will be appreciated that at least one setscrew 35 is advanced intothe threads 36 to clamp the stud 25 in position on the cable 135′ asshown in FIG. 4 to temporarily adjust the length of TV cable 135′ priorto road testing. Utilizing this method the time at which transmissionshifting occurs relative to engine revolutions per minute (rpm) can befine-tuned, which often requires several adjustments of the TV cablelength and repeated road tests.

Once the appropriate length of TV cable 135′ is established, the swagefastener 26 is permanently installed by crimping it to cable 135′ with aswaging tool (not shown). Swage fastener 26 is crimped or swaged ontocable 135′ with a minimum of 25 foot pounds using a swaging tool, whichpermanently fuses the fastener 26 to the cable 135′. Since such swagingtools are well known in the art, further detailed discussion thereof isnot deemed necessary.

Thereafter, the setscrew 35 is loosened and the setscrew fastener 28 issnapped off at the shear zone 30 by a suitable tool such as pliers andremoved from the TV cable 135′. Any excess TV cable 135′ is also trimmedoff and discarded.

Thus, it can be seen that the present TV Cable Assembly 10 provides areplacement TV cable 135′ that permits the reuse of serviceablecomponents such as the two-part OEM cable housing 115 and linkage clip120 components, which substantially reduces part replacement/labor coststo the consumer.

The present TV Cable Assembly also provides a universal fit to severaldifferent GM transmissions, which resolves the problem of ordering aprefabricated TV Cable Assembly designed for a specific transmission. Inaddition, the adjustment stud 25 of the present invention allows shifttiming to be fine-tuned by repeated adjustments to the length of thereplacement cable 135′ prior to permanent installation without damage tothe TV cable.

Although not specifically illustrated in the drawings, it should beunderstood that additional equipment and structural components will beprovided as necessary and that all of the components described above arearranged and supported in an appropriate fashion to form a complete andoperative Throttle Valve Cable Assembly and Method of Use incorporatingfeatures of the present invention.

Moreover, although illustrative embodiments of the invention have beendescribed, a latitude of modification, change, and substitution isintended in the foregoing disclosure, and in certain instances somefeatures of the invention will be employed without a corresponding useof other features. Accordingly, it is appropriate that the appendedclaims be construed broadly and in a manner consistent with the scope ofinvention.

1. A method of repairing an original equipment manufacture throttlevalve cable assembly within an automatic transmission of a land vehicle,wherein the transmission includes a throttle valve having a throttlevalve control lever connected to a throttle linkage rod, wherein thethrottle valve cable assembly is mechanically attached to the throttlevalve control lever, said method comprising the steps of: providing areplacement throttle valve cable assembly including a universal throttlevalve cable, a throttle valve cable housing, a linkage clip, a cableconnector and an adjustment stud comprising a swage fastener and asetscrew fastener interconnected by an undercut shear zone; removing theoriginal equipment manufacture throttle valve cable from said throttlevalve cable housing; inserting said universal throttle valve cable intosaid throttle valve cable housing; securing said universal throttlevalve cable at a first end thereof to the throttle valve control leveron the transmission; sliding said linkage clip and said adjustment studonto a second end of said universal throttle valve cable; connectingsaid linkage clip to the throttle linkage rod; adjusting the length ofsaid universal throttle valve cable to adjust transmission shiftperformance; and installing said adjustment stud permanently after thelength of said universal throttle valve cable is properly set.
 2. Themethod of claim 1 wherein the step of adjusting further includes thesteps of: attaching said adjustment stud onto said universal throttlevalve cable using the setscrew fastener to temporarily set the lengththereof; testing the shifting characteristics of the transmission; andchanging the length of said universal throttle valve cable until thedesired shifting characteristics of the transmission are obtained. 3.The method of claim 2 wherein the step of installing further includesthe steps of: swaging said swage fastener onto said universal throttlecable in a position corresponding to the desired length thereof;releasing said setscrew fastener from said universal throttle cable;separating said set screw fastener from said swage fastener at saidundercut shear zone; and removing said setscrew fastener from saiduniversal throttle cable.
 4. The method of claim 3 wherein the step ofswaging is carried out by a swaging tool that permanently fuses saidswage fastener to said universal throttle cable.
 5. The method of claim3 wherein the step of separating is carried out by a manually-operatedtool such as pliers.